Conventionally, photoacoustic imaging apparatuses that image the interiors of living organisms utilizing the photoacoustic effect are known, as disclosed in U.S. Patent Application Publication No. 20050004458 and X. Wang et al., “A High-Speed Photoacoustic Tomography System based on a Commercial Ultrasound and a Custom Transducer Array”, Proc. of SPIE, Vol. 7564, pp. 75624-1-75624-9, 2010. Photoacoustic imaging apparatuses irradiate pulsed light such as pulsed laser beam into the living organisms. Biological tissue that absorbs the energy of the pulsed light generates acoustic waves by volume expansion thereof due to heat. The acoustic waves are detected by an ultrasound probe or the like, and visualizations of the interiors of the living organisms is enabled based on the electrical signals (photoacoustic signals) obtained thereby.
Photoacoustic imaging methods construct images based only on acoustic waves that radiate from specific light absorbers. Therefore, photoacoustic imaging is favorably suited to image specific tissue within living organisms, such as blood vessels. Application of photoacoustic imaging to image and display blood vessels during surgery humans to enable confirmation of the positions of the blood vessels is being considered. In the case that photoacoustic imaging is applied to such a use, so called volume data that represent two dimensional regions of subjects are generated based on photoacoustic signals that represent two dimensional regions of the subjects, and tomographic images of desired cross sections are constructed based on the volume data, as disclosed in U.S. Patent Application Publication No. 20100031662.